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Electrochemical Sensing for a Rapidly Evolving World

Mullen, Max Robertson
http://orcid.org/0000-0001-5127-646X
http://rave.ohiolink.edu/etdc/view?acc_num=osu1440408652

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Chemistry.
This dissertation focuses on three projects involving the development of harsh environment gas sensors. The first project discusses the development of a multipurpose oxygen sensor electrode for use in sealing with the common electrolyte yttria stabilized zirconia. The purpose of the sealing function is to produce an internal reference environment maintained by a metal/metal oxide mixture, a criteria for miniaturization of potentiometric oxygen sensing technology. This sensor measures a potential between the internal reference and a sensing environment. The second project discusses the miniaturization of an oxygen sensor and the fabrication of a more generalized electrochemical sensing platform. The third project discusses the discovery of a new mechanism in the electrochemical sensing of ammonia through molecular recognition and the utilization of a sensor taking advantage of the new mechanism. An initial study involving the development of a microwave synthesized La0.8Sr0.2Al0.9Mn0.1O3 sensor electrode material illustrates the ability of the material developed to meet ionic and electronic conducting requirements for effective and Nernstian oxygen sensing. In addition the material deforms plastically under hot isostatic pressing conditions in a similar temperature and pressure regime with yttria stabilized zirconia to produce a seal and survive temperatures up to 1350 oC. In the second project we show novel methods to seal an oxygen environment inside a device cavity to produce an electrochemical sensor body using room temperature plasma-activated bonding and low temperature and pressure assisted plasma-activated bonding with silicon bodies, both in a clean room environment. The evolution from isostatic hot pressing methods towards room temperature complementary metal oxide semiconductor (CMOS) compatible technologies using single crystal silicon substrates in the clean room allows the sealing of devices on a much larger scale. Through this evolution in bonding technology we move from performing non-scalable experiments to produce one sensor at a time to scalable experiments producing six. The bonding methods we use are compatible with wafer scale processing. Practically speaking this means that the oxygen sensor design is scalable to produce thousands of sensors from one single bond. Using this bonding technology we develop a generalized sensing platform that could be used for a variety of sensing applications, including oxygen sensing, but also potentially involving CO2 or NOx as well. Future efforts will involve completing of O2 sensor construction and adaption of the design for CO2 and NOx sensing. The final project focuses on a novel ammonia sensor and sensing mechanism in Ag loaded zeolite Y. The sensor resistance changes upon exposure to ammonia due to the molecular recognition of Ag+ and ammonia, producing Ag(NH3)x+ species. The sensing mechanism is a Grothuss like mechanism based on the hoping of Ag+ centers. The hopping frequency of Ag+ changes upon introduction of ammonia due to the reduced electrostatic interactions between Ag+ and the negatively charged zeolite framework upon formation of Ag(NH3)x+. The change in hopping frequency results in a measurable change in impedance.
Prabir Dutta (Advisor)
289 p.
Chemistry; Materials Science
electrochemical sensor; oxygen; oxygen sensor; ammonia; nitric oxide; NOx; emissions; high temperature; harsh environment; MEMS; zirconia; hydrophilic bonding; direct bonding

Recommended Citations

Citations

  • Mullen, M. R. (2015). Electrochemical Sensing for a Rapidly Evolving World [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440408652

    APA Style (7th edition)

  • Mullen, Max. Electrochemical Sensing for a Rapidly Evolving World. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1440408652.

    MLA Style (8th edition)

  • Mullen, Max. "Electrochemical Sensing for a Rapidly Evolving World." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440408652

    Chicago Manual of Style (17th edition)

osu1440408652
932
© 2015, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.
Release 3.2.12